An elevator car is moved in the elevator hoistway e.g. with suspension ropes traveling via the traction sheave of the hoisting machine of the elevator. When the elevator runs in the heavy direction, the force effect of the hoisting machine of the elevator is parallel with the direction of movement of the suspension ropes of the elevator car that travel on the traction sheave. In this case the hoisting machine of the elevator receives electrical power from the electricity network, e.g. through a frequency converter. When the elevator runs in the light direction, the force effect produced by the hoisting machine of the elevator is instead in the opposite direction with respect to the direction of movement of the suspension ropes traveling on the traction sheave. In this case the hoisting machine of the elevator brakes the movement of the elevator car. The electrical power of the hoisting machine of the elevator produced in motor braking can be returned back to the electricity network e.g. by means of the network inverter rectifier of the frequency converter.
Since the power to be taken from the electricity network/to be returned to the electricity network during the acceleration phase of the heavy drive direction of the elevator and, on the other hand, during the deceleration phase of the light direction of the elevator increases to be very large, a temporary storage for energy comprising e.g. supercapacitors can be added in connection with the frequency converter supplying the hoisting machine of the elevator, which temporary storage supplies and also receives a set part of the total power of the hoisting machine of the elevator. One such solution is presented in publication U.S. Pat. No. 6,742,630 B2.
The power supply particularly in high-powered elevator systems supplying power to the public electricity network is conventionally taken to bypass the electricity distribution network of the building by connecting the elevator system to the public electricity network with its own separate electricity connection. In certain countries the power supply to the public electricity network is billed according to the amount of power to be supplied, in which case the costs of an electricity connection of a high-powered elevator system particularly can be considerable.